This invention relates to high speed surgical instruments and particularly to mechanism for providing a high speed drill having clutching mechanism for holding and locking cutters or tool bits into the surgical drill or attachment used for surgical procedures, with the feature of reducing the diameter of the cutting end to provide visualization to the user and to the combination of clutch mechanism and a unique designed cutter end for coupling the cutters tool bit to the surgical drill and/or attachment in the absence of mechanical moving parts. The surgical instrument includes unique bearings for supporting a cutter driven by a high speed drill, the cutter includes judicious cut out portions at the proximal end that cooperates with the clutch mechanism in the drill or in an attachment which may be bent and driven by the drill motor with the benefit that the diameter of the distal end of the attachment is made smaller than the diameter of the distal end of heretofore known surgical instruments.
The following patent applications, contemporaneously filed with this patent application and assigned to the same assignee, relate to the subject matter of this patent application and are incorporated herein by reference. They include the patent application entitled xe2x80x9cBearings for Surgical Instrumentsxe2x80x9d filed by Eddy H. Del Rio, Douglas A. Perry, Jose M. Lamanna, and Thomas D. Anspach, U.S. patent application Ser. No. 09/962,989 and the patent application entitled xe2x80x9cMiniature Cutter Shaft Configurationxe2x80x9d filed by Eddy H. Del Rio, Douglas A. Perry, Jose M. Lamanna and Thomas D. Anspach, U.S. patent application Ser. No. 09/962,461, now issued as U.S. Pat. No. No. 6,607,533.
The surgical drill typically accommodates sundry tool bits such as cutting burrs, saw blades, etc, (cutters) and different sizes thereof and during a surgical procedure different tool bits and sizes may be required for use with the surgical drill. It is therefore necessary for the surgical drill or attachment sometimes referred to as a Micro Dissection Attachment (MDA) to provide means for coupling the tool bit easily and timely with a minimum of time required to remove the incumbent tool bit and replace it with a new one.
This invention constitutes an improvement on surgical drills and/or attachments by incorporating a unique design within the drill and/or attachment so as to be capable of easily locking the cutter in place. This invention is characterized as simple to assemble and disassemble, requiring minimum amount of time for performing these function, while having the ability to reliably secure or lock the cutter in the clutch mechanism. In accordance with this invention the tool bit is inserted in the surgical drill or attachment to a point beyond where the operator feels a slight force exerted by a latching spring and slightly rotates the tool bit to its locked position. The operator, of course, has no limitations as to when the rotation of the tool bit starts when inserted into the attachment and/or drill, except at the end of the travel. The removal is merely by turning and pulling on the tool bit simultaneously in the direction for removal from the drill or attachment. We have found that the assembly and disassembly, with a minimum of experimental time or leaning time to obtain the requisite skill, the procedure is almost instantaneous. The rotating mechanism of the drill and/or attachment needs to be held stationary during this procedure. Obviously, as is apparent from the above paragraphs, the clutch mechanism does not require movable parts as is typically utilized on drills that lock the tool bit into place.
U.S. Pat. No. 5,405,348 granted on Apr. 11, 1995 to William E. Anspach, Jr. and Eddy H. Del Rio, the joint inventor of the present application, and entitled xe2x80x9cSurgical Cutting Instrumentxe2x80x9d exemplifies the cutters to which this invention pertains. In this patent it will be appreciated that the proximate end of the cutter fits into jaws of a clutch that is activated mechanically by positioning the jaws radially inward to bear against the outer surface of the cutter shaft to secure it in place during the drilling procedure and the jaws are retracted to release the cutter. Obviously, in the heretofore known mechanism of the type known and that being described herein, this procedure or similar procedure for assembly and disassembly of the cutter is not only cumbersome but is also time consuming. This invention constitutes an improvement of this type of mechanism by incorporating within the drill and/or attachment a unique attachment design for automatically retaining and locking the drill bit or cutter and which clutch mechanism is characterized by avoiding the typical manually operated clutching mechanism.
The invention is best described as having a combination of features that reduces the diameter of the support for the cutter to improve visibility for the surgeon, permits easy assembly and disassembly of the cutter or tool bit in a efficacious high speed surgical drill.
An object of this invention is to provide an improved clutch design for surgical drill and/or attachments wherein the proximal end of the cutter is configured to be easily assembled and disassembled in the unique designed automatic clutch mechanism.
A feature of this invention is that the clutch mechanism includes a hair pin shaped spring extending transversely through the wall of a rotating spindle or shaft of the drill and/or attachment to bear against the proximal end of the shaft of the cutter so as to bias the spindle or drill shaft to lock the cutter against a lock pin that also extends laterally into the bore of the spindle or drill shaft.
A clutch mechanism for a surgical drill or attachment that is characterized as relatively simple to fabricate, relatively inexpensive, easy to install the cutter into the clutch mechanism and to remove therefrom, is reliable to rotate with the drill motor and is rotatable in a clockwise and/or counterclockwise direction, and requires no mechanically moving jaws that are typically used with locking clutches.
A feature of this invention is an improved clutching mechanism in combination with a cutter with the cutter having a unique slot and groove configuration that mates with a generally U-shaped hair spring and pin for facilitating the assembly and disassembly of the cutter while locking the same and permitting clockwise and/or counterclockwise rotation.
Another feature is an improved attachment for a high speed surgical drill including a unique clutch in the attachment mating with a judicious groove arrangement formed on the proximal end of the cutter and for being supported in a reduced diameter tube attached to the attachment which reduction in diameter is a result of a unique bearing. The bearing is made from a polyimide resin/graphite compound that is formed in a journal bearing with a polygon shaped straight through central bore. The square bore configuration in a journal bearing made from a polyamide/graphite (60/40 ratio) resulted in a 3 mm diameter tube at the distal end, providing an efficacious surgical cutter instrument permitting the surgeon a line-on-line vision of the cutter at the cutting cite.